(a) Field of the Invention
The present invention relates to a cassette for loading a substrate, and more particularly, to a cassette for loading a substrate, in which a direction of taking in and out the substrate for a flat panel display device can be selectively changed.
(b) Description of the Related Art
In general, a liquid crystal display (LCD) device, a plasma display panel (PDP) device, or the like flat panel display device essentially includes a flat display panel that a pair of transparent substrates are faced and attached with each other with an intrinsic fluorescent or polarization layer sandwiched therebetween. Such a panel is configured by many times repetitively undergoing a deposition process for forming a thin film of a predetermined material, a photolithography process, and an etching process. Besides, there are involved various processes such as cleaning, assembling, cutting, etc.
To undergo these respective processes, the substrates are carried and supplied to equipment corresponding to each process. At this time, a cassette is used for loading a plurality of substrates in order to reduce time and effort to be taken in carrying and keeping the substrates. The existing cassette forms a minimal unit of keeping and carrying the substrates in manufacturing the flat panel display device.
FIG. 1 is a perspective view of a general cassette for loading a substrate.
As shown therein, a cassette for loading a substrate (hereinafter, referred to as a ‘cassette: C’) includes top and bottom plates 14 and 16 forming the top and bottom horizontal surfaces of the ceiling and the floor; an entrance 12 opened by connecting corresponding edges of the top and bottom plates 14 and 16; opposite lateral surfaces 18, 20 facing each other with respect to the front entrance 12 so as to form an interior space for loading the substrate; and a back surface 22 opposite to the entrance 12.
The opposite lateral surfaces 18, 20 and the back surface 22 include a plurality of frame bars 32a, 32b, 32c, 34a, 34b, 34c and a support frame bar 36. The frame bars 32a, 32b, 32c, 34a, 34b, 34c include a plurality of side slot pins 42 at regular intervals, which horizontally protrude from insides thereof in a direction of facing each other. The support frame bar 36 forming the back surface 22 of the cassette 10 includes a plurality of support bars 46 at the same intervals as the side slot pins 42, which horizontally protrude toward the entrance 12. At this time, one end of the support bar 46 is formed with a peak 44 for not direct contact but point contact with the substrate.
Thus, the substrate (not shown) are supported at opposite edges by the side slot pins 42 provided at opposite sides and corresponding to each other, and transversely supported by the support bar 46, so that they can be loaded according to respective layers.
The substrate to be kept in the cassette C is taken in and out as follows. First, as shown in (a) of FIG. 2, the substrates G carried from a carrying line L1 of the preceding process are loaded to the inside of the cassette C by a gantry robot R. As shown therein, an end part of the substrate G facing a front of the carrying line L1 is loaded to face toward a front opening of the cassette C, and sent to the following process by a cassette carrying device (not shown)
Then, shown in (b) of FIG. 2, the substrate G loaded to the cassette C as is taken out by the gantry robot R through the front opening of the cassette C and sent to a carrying line L2 of the following process. However, in the case that the substrate G is directly carried by the gantry robot R from the cassette C to the carrying line L1 of the following process, a front and back direction of the substrate G is reversed because the end part of the substrate G facing the front opening of the cassette C faces a back of the carrying line L2 of the following process.
As shown therein, a turn table T for a 180-degree turn of the substrate G is provided between the cassette C and the following carrying line L2, and the glaess G taken out from the cassette C by the gantry robot R is put on the turn table T. Then, the turn table T is turn 180 degrees, and the substrate G is sent by the gantry robot R from the turn table T to the carrying line L2 of the following process. Accordingly, there is a problem in that the number of processes increases.
Further, the substrate G may be handled for the 180-degree turn by a worker of a processing line. However, in this case, the substrates may be misaligned and be easily damaged.